Bearing structure



April 15, 1941.

J. P. NORTON BEARING STRUCTURE Filed May 9, 1939 Patented Apr. 15, 1941BEARING STRUCTURE James P. Norton, Beverly, Mass., assignor to TheParkersburg Rig & Reel Company, Parkersburg, W. Va., a corporation ofWest Virginia.

Application May 9, l1939, Serial N0. 272,687

2 Claims.

This invention relates to bearing structures, and more particularly to abearing for use 1n the pitman constructions employed in oil well pumpingapparatus. n

While the invention is of general application in bearings and analogousstructures it is particularly advantageous for use in connection withthe driving of mechanismsy wherein the bearings are subjected tosubstantial shock loads as is true, for example, inthe pitm-anconnections of oil well pumping units.

In such a construction the take-ofi pitman is subjected to constantshock loads during the pumping operations and frequently the pitman isplaced alternately in tension and compression, thus reversing the shockloads on the bearings. It is therefore desirable and in fact almostessential that the bearings lbe made into integral assemblies with thepitman stems.

In the past attempts have been made to attach pitman and similarbearings to the structural member which supports them by means of bolts,key arrangements, etc. Such methods of attachment have never proved tobe very satisfactory since the bearings have a tendency to work looseand there is always the danger that the attachment bolts may fail fromfatigue or from being pulled up too tight. Failure of the bearingconnection can` easily cause the failure of the entire pumping rig andalso cause losses due to the loss of production of oil, etc.

A bearing design can be worked out to overcome these difculties by usingaccurately machined fits, etc. that would assure the bearing attachingmeans remaining tight, but the expense of such a design is prohibitive.'it also would be possible to make a design using such large attachingbolts or pins that the possibility of failure could be eliminated.However, the expense of such a design also would be prohibitiveespecially if, in. addition, precision machined ts were also employed.If precision machined fits and generous load supporting surfaces werenot used the connections would soon'work suiiiciently loose to causeobjectionable relative movement and knocks while in service.

It has been found that the most satisfactory and practicalconstructionin the past has been toY employ cast steel bearing housingsand to weld the structural steel members directly to the difficult tolayY a good weld and one that is` homogeneous with the metalof ,theparts being welded.

Moreover, steels of diiferent carbon content also are diicult to weldtogether as any appreciable dierence in carbon content necessitates somedifference in welding technique. The structural elements. to which thebearing housings are connected are usually formed of rolled structuralsteel having a relatively low carbon content. The carbon content of thesteel castings from which the housings are made is not uniform from onecasting to another and at times may be considerably higher than that ofrolled steel. Moreover, aside from the diiculty of laying asmooth-appearing weld on cast steel, it is generally impossible to tellfrom the appearance of the weld -how good the weld may be and with caststeel parts reliance must be placed upon the skill of the welderfor anyassurance that the calculated load capacity of the weld will beobtained.

It is impracticable in most structures of this kind to consider X-rayingor making similar tests on the welds to determine the character thereof.A defective weld obviously may fail of fatigue under load. Moreover,applying heat to a cast steel bearing housing may result in warpage ofthe casting and misalignment of the bearing bores. To avoid this it isfrequently necessary to design housings, which are to be Welded, so thatthe welded surfaces are an appreciable distance from the bearing bore,thus resulting in a larger and more expensive bearing than wouldotherwise be required.

An important object of the invention is to provide a novel bearingstructure which combines the use of a cast iron casting with steelinserts of such nature and form as to provide a nished bearing structurewhich readily may be connected to the structural element associatedtherewith.

A further object is to provide a bearing structure of this characterwherein al1 loads are transmitted through the steel inserts and whereinthe cast iron casting is relieved of all tensile loads, thus permittingthe use of a lighter bearing structure.

A further object is to provide a bearing structure wherein the steelinserts completely surround the shaft associated with the bearing lwhereby it is adapted to transmit all loads between the shaft and thestructural element to which the bearing is connected, the structurelending itself particularly well to the withstanding of shock loadsregardless of the direction of application of such loads around the axisof the bearing.

A further object is to provide av bearing structureof this characterwherein the steel inserts may be made of the same form of steel asA thestructural element to which the bearing structure is to be connected,for example, rolled structural steel, thus facilitating the provision ofan efcient weld between the steel inserts and the structural elementreferred to.

A further object is to provide a bearing structure wherein the steelinserts will be bonded to the cast iron casting and wherein the onlytorque required to be transmitted by the bond between the inserts andcasting is that necessary to over come the friction of the bearing,which is relatively small.

A further object is to provide such a bearing wherein the nature of theinserts is such as to provide a keying effect between the inserts andthe casting.

Other objects and advantages of the invention will become apparentduring the course of the following description.

In the drawing I have shown two embodiments of the invention. In thisshowing:

Figure 1 is a side elevation of a pitman connection employed in oil wellpumping apparatus, parts being broken away and parts being shown insection,

Figure 2 is a section on line 2-2 of Figure 1, parts being b-roken awayand parts being shown in elevation,

Figure 3 is an enlarged detail perspectiveview of one of the steelinserts, and,

Figure 4 is a detail sectional View approxif mately in the plane of oneof the inserts showing a modified form of insert.

Referring to the drawing the numeral I9 designates any form ofstructural element to which power is to be applied such as the walkingbeam of an oil well pumping apparatus. The structural element I0 isshown as being provided with depending spaced. ears II apertured as atI2 to receive a shaft I3 through which the power '1s transmitted to theelement I0. A depending arm I4 is carried by one of the ears II and isfixed thereto as at I5, the arm II having a close fit with a reducedextension I6 on the end of the shaft to prevent the turning of the shaftwith respect to the ears II.

The invention is shown as being applied to the upper and lower ends of apitman indicated as a whole by the numeral II. This pitman is shown asbeing in the form of a structural member I8 preferably of rolled I-beamsection. At the upper end of the body of the pitman, filler blocks I9are welded to the edges of the flanges of the pitman body to provideseats to which are connected the inserts to be described. The plates I9also are preferably formed of rolled steel and may be omitted where thepitman or other structural element presents surfaces of sufficient areato be directly welded to the inserts, as will become apparent.

A cast bearing body 20, preferably formed of cast iron, is arrangedbetween the lower ends of the ears II and carries a bearing bushing 2|receiving the shaft I3. 'Ihe cast body 2Il is formed to facilitatelubricationof the bearing surfaces. It will be noted that the bearingbody is provided with a lubricant receiving chamber 22 into whichlubricant may be introduced by the removal of a plug 23 preferablyvented as at 24. The cast body is formed with longitudinal lubricantpassages 25 for supplying lubricant to radial lubricant openings 26formed in the bushing 2|. Lubricant packing 21 may be arranged in thecast body 20 at the ends of the bushing 2I.

A pair of steel inserts each indicated as a when the plates whole by thenumeral 28 are cast in the body 20 of the bearing and are employed fortransmitting forces between the shaft I3 and pitman body I8. One of theinserts is shown in detail in Figure 3 and comprises a substantiallycircular body 29 having a general circular opening 39 therein which,when cast into the body 20, has its axis concentric with the axis of thebushing 2|. The opening 3l) is preferably irregularly shaped to providethe effect of keying it with respect to the cast body 20, the opening 30preferably being so shaped as to facilitate the flowing of the metalfrom which the casting 20 is made into the opening 30, and this openingpreferably is also soshaped as to avoid any concentration of stress incorners. As shown in Figure 3, therefore, the edges of the opening 30are arcuately cut back as at 3l to form recesses to receive the metal ofthe housing 2i), and these recesses join the main portion of the opening39 by curved surfaces 32 thus eliminating any edges in the opening 30.If desired, each insert may be provided with additional small openings33 into which the metal of the body 29 can flow to provide an additionalanchoring effect between the inserts and the cast body 29. Theseopenings are not necessary and the metal flowing thereinto is not reliedupon to carry any load.

Each insert is provided with a radial extension 34 preferably slightlywider than its associated plate I9 or other surface to which it is to beconnected. The housing 29 is provided with two inserts of the characterreferred to and the space between the projections of these ins-erts isequal to the space between the remote faces of the plates I9 and arewelded thereto. The inserts are preferably made of rolled steel and maybe flat as indicated in Figures 2 and 3. The plates I9 and pitman bodyI3 are also made of rolled steel, and accordingly the projections 34 maybe readily and efficiently welded to the plates I9. The similarity inthe material of the pitman body I8 and plates I9 likewise facilitatesthe welding of the plates I9 to the pitman body i8 I9 are employed. Itwill be noted that the circular portion of each insert completelysurrounds the bushing 2l and is spaced therefrom by the intervening bodyof cast iron within each opening 39. Accordingly any forces transmittedradially to or from the inserts will be taken up by the inserts withouttransmitting any tensile strains whatever to the cast body 2U. I

A similar bearing structure may be arranged at'the lower end. of thepitman body I3. As a matter of fact, the lower bearing structure may besubstantially identical with the bearing structure just described andneed not be referred t0 in detail. Accordingly similar parts have beendesignated bythe same reference numerals. If desired, each bearinghousing may be provided with a plug 35 from which lubricant may bedrained from the chamber 22, such a plug being shown in connection withthe lower bearing structure.

The shaft I 3 of the lower bearing structure may be connected to anydesired element through which the pitman may be driven or to which thepitman may transmit power. In the present instance, the structure towhich the lower shaft I3 is connected has been represented by a pair ofplates 36 surrounding the shaft I3 and welded or otherwise connected tothe body of the structure referred to. One ofthe plates 3E is connectedwith an arm 31 similar to the arm I4 previously described, and operativefor preventing turning movement of the shaft I3 with respect to theelements 36.

The openings 30 in the inserts referred to need not be of any particularshape or contour but they are preferably other than round so as toobtain a keying effect with' respect to the casting so that the bondbetween the inserts and the casting does not have to be relied upon totransmit torque. Obviously the opening 30 may be made in an infinitenumber of shapes. If desired, the shape of the opening may be such as toincrease the fusing or bonding of the steel inserts with the cast ironcasting as well as to provide the desired keying effect.

For example, an insert plate may be made as shown in Figure 4 andindicated by the numeral 38, the insert being provided with an opening39 formed with a series of teeth around the circumference of the opening`so that the points projecting radially inwardly will be raised moredefinitely to the fusing temperature of the metal by` the molten ironfrom which the bearing body 20 is cast. 'I'he insert in Figure 4 isotherwise similar to the insert previously described, being providedwith the projecting portion 40 by which the insert may be welded to itsadjacent structure.

The operation of the construction will be apparent from the foregoingdescription. The steel plates 28 are set directly in the mold before thebearing body 20 is cast. When the iron is poured, it flows around theplates 28 and ntothe openings 30, and shrinks against land fuses withthe steel of the inserts. the inserts will remain tightly in position,if by any chance they do not bond with and in fact become integral partsof the bearing housing by fusion of the metal, the irregular shaping ofthe opening 30 insures a keying effect between .the v inserts and thebearing body,

'I'he only torque required to -be transmitted by the lbon-d between theinserts and the casting is that necessary to overcome the friction ofthe bearing and this friction, for normal operation, is relativelysmall. However, the keying effect between the inserts and the bearingbody is sufcient to overcome increased bearing friction in the event thebearing is set up too tightly. Therefore the bonding effect between theparts need not be wholly relied upon, but such bonding actually doestake place so that the bearing structure is, in effect, an integralstructure.

Particular attention is invited to the fact that the steel inserts formrings completely surrounding the casting, the opening in each platebeing preferably symmetrical and generally concentric with the axis ofthe bearing to uniformly transmit forces between the shaft and the steelinserts. Forces exerted in any direction are transmitted by the steelinserts. For example, in the pitman arrangement shown the pitman bodymay be placed under either tension or compression and in either case thesteel inserts at Ithe upper end of the pitman will directly transmitlthe forces radially to the shaft I3 to operate the walking beam orother structure I0. The cast iron of the body I0, therefore, is neverrequired to transmit any tensile load. The steel inserts therefore actas force transmitting elements and they also reinforce the cast iron.Accordingly, since it is not required to carry the load, the castingneed not be of high strength cast iron and can be made las light insection as other details of the design permit,

As a further assurance that The lpresent construction also effects avery appreciable saving in cost. It will be evident that in comparisonwith an all cast iron design there is a considerable saving in the sizeand 4weight of the casting due to the reinforcing of the casting by thesteel inserts and by the transmission of forces through the inserts. Theconstruction also Ipermits the load transmitting inserts and theirprojections 34 to be made of the same material as the structuralelements to which they are to be welded, thus permitting the laying of aperfect weld and eliminating the necessity for the use of attachingbol-ts or other similar devices.

As compared with an all cast steel bearing structure the presentconstruction also effects some saving in size and weight. As theconstruction lends itself to a simpler design, a very appreciable savingin cost is effected due to the fact that cast steel usually costs fromfour to five times that of cas-t iron or rolled steel.

It is to be understood that the forms of the invention herewith shownand described are to be taken as preferred examples of the same and thatvarious changes in the shape, size and arrangement of parts may beresorted to Without departing from the spirit of the invention or thescope of the subjoined claims.

I claim:

l. A bearing structure for a lpitman of a deep well pumping mechanism,comprising a cast -body having a bushing therein, and a pair of spacedrigid parallel inserts embedded in said cast body intermediate the endsthereof and perpendicular to the axis of said bushing, said insertsbeing formed of a readily weldable metal of higher l tensile strengththan said cast body and each comprising a substantially circular portionsurrounding the axis of said shaft concentric therewith, the circularportion of each insert having a concentric opening of greater diameterthan the internal diameter of said cast body whereby the metal of thelatter extends through such opening, said cast body at each side of eachinsert being of greater diameter than the opening in said insert wherebythe metal of said body extends over and circumferentially around atleast a portion of each side face of said inserts, said inserts havingattachment portions extending radially outwardly of said cast body.

2. A bearing structure for a pitman of a deep well pumping mechanism,comprising a cast body having a bushing therein, a pair of rigid flatspaced' parallel inserts embedded in said cast body at points spacedfrom the ends thereof and perpendicular to the axis of said bushing,said inserts being formed of a readily weldable metal of higher tensilestrength than said cast body, each insert comprising a substantiallycircular portion surrounding the axis of said shaftconcentric therewithand having a concentric opening of greater diameter than the internaldiameter of said cast body whereby the metal of thel latter extendsthrough such opening, said cast body at each side of each insert beingof greater diameter than the opening in the insert whereby the metal ofthe bodyextends over and circumferentially around at least a portion ofeach side face of each insert, said inserts having attachment portionsextending radially outwardly of said cast body, and a rigid structureextending radially from said cast body and having an end portionprovided with parallel outer face portions arranged between and weldedto said attachment portions.

JAMES P. NORTONu

